If someone uses '... wrote last night ...' in a sentence, then the sentence indicates the time that it was written. If they meant that something else happened last night, they need to construct the sentence differently. It isn't ambiguous.
 Give me blood and I will give you freedom.
 Be industrious and you will succeed in life.
Constructions like these do not have the form or literal meaning of conditionals, but they serve indirectly to convey a conditional meaning. The first clause in each example is not an adjunct (your adverbial), but a main clause and thus these are compound ...
I agree that this looks like an inconsistency.
No matter how you want to classify the sentences, they have the same grammatical structure.
Give me blood.
I will give you freedom.
You will succeed in life.
You can assume that the first clauses are implied conditionals, and therefore subordinate, but ...
In my American English dialect that would not be acceptable, except as a joke between people who also speak French.
"It's not that I don't want to..." is perfectly acceptable.
"I don't want to..." use this if you are starting the conversation. "I don't want to go out for lunch, I am on a budget."